Wesley,
I'll give you a method that seemed to work for me. There seem to be many ways to sharpen these and I think success depends on each person's "hand" in the process. How much pressure you use during the process, etc. Anyway - -
I liked to use a DMT diamond stone - a medium grit. And I would sharpen 2 blades at a time flat on the stone. I would draw the heads backwards across the stone.
As the edge begins to develope use less down pressure on the head. If you go slow you can feel the sharpness.
Once you have them as sharp as you can get them on the stone - take a clean piece of brown cardboard and give the head a few strokes backwards across the cardboard to strop the edge.
Now this all takes considerably more time than the file method. But I just don't seem to have the "hand" for filing - always end up with too much pressure and loose the edge.
As it has been said many times before - you need to experiment and see which method works best for you. But it can be fun to tinker ...
Chinook